Cold‐inducible RBM3 inhibits PERK phosphorylation through cooperation with NF90 to protect cells from endoplasmic reticulum stress

Abstract

The cold-inducible RNA-binding motif protein 3 (RBM3) is involved in the protection of neurons in hypoxic-ischemic and neurodegenerative disorders. RBM3 belongs to a small group of proteins whose synthesis increases during hypothermia while global protein production is slowed down. To investigate the molecular mechanisms underlying RBM3 action, we subjected hippocampal organotypic slice cultures from RBM3 knockout mice to various stressors and found exuberant signaling of the endoplasmic reticulum (ER) stress pathway PRKR-like ER kinase (PERK)-eukaryotic translation initiation factor 2α (eIF2α)-CCAAT/enhancer-binding protein homologous protein (CHOP) as compared with wild-type mice. Further, blocking RBM3 expression in human embryonic kidney HEK293 cells by specific small interfering RNAs increased phosphorylation of PERK and eIF2α, whereas overexpression of RBM3 prevented PERK-eIF2α-CHOP signaling during ER stress induced by thapsigargin or tunicamycin. RBM3 did not affect expression of the ER stress sensor immunoglobulin binding protein/GRP78. However, based on affinity purification coupled with mass spectrometry, coimmunoprecipitation, and proximity ligation assay, we revealed that nuclear factor 90 (NF90) is a novel protein interactor of PERK and that this interaction is essential for RBM3-mediated regulation of PERK activity, which requires an RNA-dependent interaction. In conclusion, our data provide evidence for a central role of RBM3 in preventing cell death by inhibiting the PERK-eIF2α-CHOP ER stress pathway through cooperation with NF90.

Overexpression of the long noncoding RNA TUG1 protects against cold‐induced injury of mouse livers by inhibiting apoptosis and inflammation

“…It has been reported that damage at the ER and mitochondria are implicated in cold stress‐induced apoptosis . So we evaluated whether TUG1 attenuated cold‐induced apoptosis through the inhibition of ER stress pathway or (and) mitochondria apoptosis pathway in cold‐stimulated HC and LSECs.…”

Adaptive preconditioning in neurological diseases – therapeutic insights from proteostatic perturbations

“…Adaptive UPR responses in human neurons were required for hypothermic protection against both oxidative and ER stress – important contributors to acute and chronic neuronal injury (Rzechorzek et al, 2015). However, in contrast to previous work in prion-diseased mice (Moreno et al, 2012), Rzechorzek et al showed that PERK was an important contributor to neuroprotective adaptation of the UPR and proposed that cold-shock proteins would interact with this pathway – a hypothesis recently supported for cold-inducible RNA binding motif-3 (RBM3) in vitro (Zhu et al, 2016). …”

RNA binding motif protein 3: a potential biomarker in cancer and therapeutic target in neuroprotection

“…RBM3 exerts its cell-protective effects by modulating canonical PERK-eIF2α-CHOP signaling [82]. Under sustained ER stress, PERK and eIF2α phosphorylation is inhibited in cells overexpressing recombinant RBM3, which reduces CHOP expression and ultimately prevents cell apoptosis [83]. In contrast, PERK and eIF2α phosphorylation is dramatically increased in cells with silenced RBM3 by specific siRNAs, indicating that RBM3 may function as an inhibitor of the PERK-eIF2α-CHOP signaling pathway.…”